Effects of antimycin a plus 2-deoxyglucose on uptake and vesicular storage of serotonin in human platelets

The effects of the metabolic poisons antimycin A (4.1 μg/ml) and 2-deoxyglucose (32.2 mM) on the uptake and vesicular storage of serotonin in washed human platelets have been examined. Within 15 seconds after the addition of the metabolic poisons, H³-5HT begins to move from vesicles into the cytoplasm; by 30 minutes after poison addition, essentially all the platelet 5HT appears to be cytoplasmic. The metabolic poisons also act rapidly to decrease plasma-membrane uptake of H³-5HT from the extracellular medium by approximately 20% within 1 minute after their addition. This may represent a direct effect rather than one resulting from altered cytoplasmic or vesicular 5HT, since platelets with <10% of the normal number of vesicular storage sites exhibit a similar reduction after addition of the metabolic poisons.